1. Field of the Invention
The present invention relates to a document scanning device installed in an image processing unit such as a copying machine for use in editing an image of a document.
2. Description of Related Art
Japanese Patent Application Laid-Open No. 55-89868 discloses a copying machine which is designed to easily extract and edit a necessary column from a document with a plurality of columns, for example, a list of customers' addresses. On the other hand, a copying machine disclosed in U.S. Pat. No. 4,862,216 can form an image at an area in a sub-scanning direction of a document with a color different from ones at the other areas.
These prior art copying machines are arranged to indicate a boundary between a necessary area and an unnecessary area of the image, or a boundary between image colors in the sub-scanning direction of the document. And, for indicating the boundary, a position indicating lever is provided frontwardly of a document platen in a movable manner in the sub-scanning direction of the document. The position indicating lever is of a structure, for example, described below, although various types of structures are proposed. Specifically, a white tape or the like is attached to an area where the image of the document is not read on the lower surface of a document platen glass in the sub-scanning direction, with a black lever provided below the tape. In the structure described above, the difference in reflectivity between the tape and the lever is read during the sub-scanning of the document image with the use of a part of a CCD line sensor provided for reading the document image, whereby a position indicated by the lever is recognized.
It is therefore more convenient to edit the document if the position indicating levers are provided as many as possible in the copying machine of the above-discussed structure, so that the boundary can be indicated at many points or positions.
When a list of addresses is to be copied, it hardly takes place that a constant number of necessary and unnecessary areas are always desired. In the case where a small number of areas are desired, levers not to be used amount to a lot, which should not be detected. Therefore, a retreat is arranged in the prior art copying machine such that the levers not in use are prevented from being detected, as a non-detecting area at an end of a moving area of the levers into which the unnecessary levers are accommodated. Because of the retreat it becomes impossible to use the overall area in a reading width in the sub-scanning direction of the document platen for indication by the position indicating levers. Or, the retreat necessitates an increase of the width of the copying machine in the sub-scanning direction.
Moreover, in the event that many areas of the document are to be copied after only a small number of areas thereof are edited and copied, the corresponding necessary number of levers should be taken out again from the retreat, resulting in a great trouble. And, it considerably lowers the efficiency that even the frequently-desired area is necessary to be selected at every requirement.